I.E. Effects Delivers Stereo Conversion for Harry Potter

Harry Potter fans worldwide are flocking to theaters this summer for the eighth and final installment of the wildly popular film series. Playing to great reviews, Harry Potter and the Deathly Hallows Part 2 is the first film in the franchise to be released in stereoscopic 3D. L.A.-based visual effects house I.E. Effects contributed to this complex postproduction task, providing 2D-to-3D stereo conversion for several key sequences, including some in the film’s opening scenes.

A team of over 50 artists at I.E. Effects’ L.A. and Traverse City, Michigan, facilities worked together for over six months to perfect the stereoscopic effect, making frame-by-frame adjustments to create a 3D experience for audiences.

“The purpose of good 3D is to help tell the story,” said company founder David Kenneth. “When you get it right, the stereo effect isn’t the focal point. It simply helps the audience become more absorbed in the story.”

Converting a 2D film to stereo 3D is labor intensive and requires skilled visual effects artists to create a final result that looks natural. Rather than a single image for each frame, stereo 3D content has two views – one for each eye.

Creating two separate images from a single frame requires subtle adjustments to the viewing angle for each element in the image. The process starts off with rotoscoping – manually cutting elements out of the image and then assigning them depth values to make different parts of the picture seem closer or farther away. These depth values allow the artists to reposition each element for the right and the left eyes. Once in place, the missing details for the left and right eye images need to be ‘painted in’ frame by frame.

The shots delivered by I.E. Effects for Harry Potter included both interior and exterior shots. “You have to push the 3D a lot more for exterior shots, so there’s generally a lot more painting,” said Dennis Michel, visual effects supervisor at I.E. Effects. “But the interior shots usually have a shallower depth of field, which means more subtle adjustments.”

Several shots in the opening sequence included very fine elements, such as hair blowing in the wind. “The Ollivander character (John Hurt) is a wise old wizard with wispy hair,” said Michel. “Hair is an interesting challenge for any kind of visual effects work. For this film we had a small team of artists painting and tweaking individual strands for some time until we got the stereo 3D just right.”

Defocused areas of the frame provide another challenge in the stereo conversion process. Filmmakers often use a shallow depth of field to give their work a ‘filmic’ look that draws the viewer’s attention to an area in the image. This technique creates soft focus, or even blurred foreground and background elements.

“Stereo conversion is as much an art as it is a science, so we look at every shot individually and approach it in a handcrafted way,” said Michel. “This is not something where you could just push a button and let a machine do the work.”

For rotoscoping and reassembling the images, the team at I.E. Effects uses The Foundry’s Nuke compositing system along with a set of in-house proprietary software tools that drive the workflow and link the company’s two locations. “We use automation to expedite the steps in the process, but this kind of work always comes down to the artist’s eye and a lot of patience.”

I.E. Effects opened its sister facility in Traverse City, northern Michigan, late last year. Since opening, the facility has done 2D-to-3D conversion work for such films as Green Lantern and Gulliver’s Travels, as well as the current Harry Potter film. “We’re delighted to be doing this kind of high-end artistic work here in Michigan,” said David Kenneth.

The Growth of Stereo 3D in Film

There has been some discussion in the media and the general public about the growing numbers of 3D theatrical releases. “Some people may think it’s a gimmick, but stereo 3D is here to stay,” said Kenneth. “We’ve seen a lot of sensational 3D in recent years, where objects erupt out of the screen into the audience, but gags like that get old fast. That is not what 3D is about.”

Instead of coming out of the screen, Kenneth feels that good stereoscopy is more subtle and pulls the audience into the scene, making it feel comfortable and natural. “3D is about providing an immersive experience that is as close to real life as you can get in the theater. It’s like ‘visual surround sound,’ making the story that much more immediate.”

Kenneth compares stereo 3D with earlier developments in film, which have now become established components of the craft. “Just like when movies were given sound, and then color and then special effects, 3D is a powerful addition to the filmmaker’s toolkit, and, when it’s used properly, it enhances the theater experience.”